The present invention relates to a method of regulating the charging of batteries containing a number of cells, for example NiCd cells, in which the battery is connected to a battery charger for impressing a current through the battery.
A plurality of different techniques for charging batteries containing, for example, NiCd cells are known in the art. Examples are constant current charging, constant voltage charging in which the charging current is based on the battery cell temperature and pressure, pressure and temperature charging, and pulse charging. The major advantage afforded by constant current charging is that the charger may be of extremely simple design, while its major drawbacks are those of being restricted to a temperature range of between 0.degree. and 40.degree. C. and of requiring an extremely long charging time at lower temperatures, since the permitted mean current under cold conditions is considerably lower than at room temperature. Furthermore, the charging itself takes place completely uncontrolled and without any adaptation whatever to the capacity of the cells to accept the charging energy. Constant voltage charging is also uncontrolled, but in this process the properties of the cell are utilized somewhat better. However, in this case also the charging time will be long, in particular at low temperatures. Because of the difficulties in providing pressure and temperature-sensing elements, pressure and temperature charging occurs only in extremely special and uncommon circumstances. In this case, the reason for this is that the practical obstacles are as good as insurmountable. In per se conventional pulse charging, the charging takes place in cycles of, for example, 1 Hz, the charging current being, for example, twice as great as the nominal discharging current. Pulse charging has proved to be more efficient than many other charging techniques, in particular at low temperatures. In conventional pulse charging, compensation is merely effected of poor control of the charging current of the battery. However, conventional pulse charging involves considerable charging time and relatively poor control over the different parameters.